CN102316552B - Non-network cell searching method of mobile terminal - Google Patents

Abstract

The invention discloses a method for searching a cell without a network for a mobile terminal, which includes: acquiring a wireless network search frequency band; performing a frequency band search, and entering a cell search when the frequency band search is successful; otherwise, adjusting a frequency band search cycle and entering a no-network sleep state; Carry out cell search, when the cell search is successful, end the no-network cell search process, otherwise, adjust the frequency band search cycle and enter the no-network sleep state; when the duration of the no-network sleep state reaches the adjusted frequency band search cycle, return and Perform the band search. This technical solution associates the success and failure information of the intermediate process of frequency band search and cell search as the signal change trend in the no-network environment, and uses this information to quickly track the network signal change trend and dynamically adjust the mobile terminal no-network cell search accordingly. period, while reducing the power consumption of the terminal in the state of no network search, it can quickly search for a cell when the network signal is restored.

Description

Mobile Terminal No Network Cell Search Method

Technical field:

The invention relates to the field of wireless communication, in particular to a method for searching a cell without a network for a mobile terminal.

Background technique:

In a wireless communication system, a mobile terminal always tries to camp on a suitable cell in order to obtain wireless network services. In the actual environment, due to the lack of access network coverage in the area, such as the initial stage of network construction, areas that cannot be covered due to technical or non-technical reasons, or short-term no access network coverage, such as signal coverage blind spots, network failures, etc., It may cause the mobile terminal to fail to camp in a suitable cell normally and enter the no-network state. In this case, the mobile terminal will constantly try to search and camp on a suitable or acceptable cell. This search behavior of the mobile terminal in any cell search state is called no network cell search behavior. Once any cell search If all attempts fail, the mobile terminal will still be in the state of "searching for any cell", and will repeat the above search process periodically according to a certain search method.

Referring to Fig. 1, it is a schematic flow chart of a method for searching a cell without a network for a mobile terminal in the prior art. The method includes the following steps: step 101, obtaining a search frequency band; step 102, performing a frequency band search, and entering the cell search if successful If it fails, go to step 104; step 103, perform cell search, if it succeeds, stop searching, if it fails, go to step 104; step 104, enter sleep state. When the duration of the sleep state reaches the preset search period, step 102 is repeatedly executed. The search cycle refers to the time interval between two frequency band search behaviors. The larger the search cycle, the longer the sleep state of the mobile terminal lasts, which is conducive to saving power consumption. The shorter the search cycle, the easier and faster the mobile terminal is. Perceive the recovery of network signals and search for available cells.

Through the research on the prior art, the inventors found that the search method of the mobile terminal without network in the prior art mostly uses a fixed-period search, that is, the time of the two frequency band search behaviors before and after is fixed, resulting in the selection of a longer During the search cycle, it is not conducive to quickly search for cells when the network signal is restored. When a short search cycle is selected, the power consumption of the search will increase significantly.

Contents of the invention

In order to solve the above-mentioned technical problems, the object of the present invention is to provide a method for searching a cell without a network for a mobile terminal, so that the search method can dynamically adjust the search period according to the network status of the mobile terminal, and reduce the power consumption of the search while reducing the power consumption. , to quickly search for the cell.

To achieve the above object, the present invention provides the following technical solutions:

A method for searching a cell without a network for a mobile terminal, comprising:

Obtain wireless network search frequency band;

Perform frequency band search, when the frequency band search is successful, enter the cell search, otherwise, adjust the frequency band search cycle, and enter the no-network sleep state;

Carry out cell search, when the cell search is successful, end the no-network cell search process, otherwise, adjust the frequency band search cycle and enter the no-network sleep state;

When the duration of the no-network sleep state reaches the adjusted frequency band search period, return and execute the frequency band search.

Preferably, when the frequency band search fails, the adjustment of the frequency band search period includes:

Increase the time interval between the two frequency band search behaviors before and after, and the increased duration is the first duration.

Preferably, the cell search includes:

Perform coarse synchronization, if successful, enter fine synchronization, otherwise, cell search fails;

Perform fine synchronization, if successful, enter to read system information, otherwise, cell search fails;

Read the system information, if successful, the cell search is successful, otherwise, the cell search fails.

Preferably, when the cell search fails, the adjustment of the frequency band search cycle includes:

When the coarse synchronization fails, increase the time interval between the two frequency band search behaviors before and after, and the increased duration is the second duration;

When the fine synchronization fails, reduce the time interval between the two frequency band search behaviors before and after, and the reduced duration is the third duration;

When reading the system message fails, reduce the time interval between the two frequency band search actions before and after, and the reduced time length is the fourth time length.

Preferably, when the cell search is successful, it also includes:

Report the searched available cells to the application layer, and set the frequency band search cycle to the initial value.

Preferably, the first duration is longer than the second duration.

Preferably, the fourth duration is longer than the third duration.

Preferably, the frequency band search includes:

Search for frequency bands under different access modes according to the information of no-network search frequency bands and access modes;

Calculate the received signal strength indication of the frequency points in each access mode, and obtain the frequency point power list;

Judging whether there is a frequency point exceeding the preset power threshold, if yes, the frequency band search is successful, otherwise the frequency band search fails.

Preferably, after the frequency band search is successful, the list of frequency points exceeding the preset power threshold is arranged in order of power from strong to weak;

The cell search is performed according to the order of frequency point power list from strong to weak.

Preferably, after the frequency band search is successful, the preset power threshold is updated according to the following method:

Calculate the power smoothing value of the frequency points that currently exceed the preset threshold power;

A smoothing operation is performed on the original preset power threshold and the power smoothing value of the frequency point whose power exceeds the preset threshold to obtain a new power threshold, and the newly obtained power threshold is set as the preset power threshold. By applying the technical solution provided by the embodiment of the present invention, the success and failure information of the frequency band search and the cell search intermediate process are associated as the signal change trend in the no-network environment, and when the frequency search fails and the cell search fails, adjust according to the preset formula The search period, using the information obtained from the frequency search failure and the cell search, can quickly track and respond to the network signal change trend, and dynamically adjust the cell search cycle of the mobile terminal without network accordingly, reducing the power consumption of the terminal in the state of no network search At the same time, the cell can be quickly searched when the network signal is restored.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

FIG. 1 is a schematic flow diagram of a method for searching a cell without a network for a mobile terminal in the prior art;

FIG. 2 is a schematic flowchart of a method for searching a cell without a network for a mobile terminal provided in Embodiment 1 of the present invention;

FIG. 3 is a schematic flowchart of a frequency band search method provided in Embodiment 2 of the present invention;

Fig. 4 is a schematic flowchart of the cell search method provided in the third embodiment of the present invention.

Detailed ways

In the framework of the mobile terminal's network-free cell search, the application and high-level protocols are responsible for controlling the start and termination of the network-free cell search process. According to the access mode RAT (Radio Access Technology) supported by the mobile terminal, the application and high-level selection After searching the frequency band and notifying the physical layer, it enters the sleep standby state. The physical layer protocol is responsible for the search process of no-network cells. Only when an available cell is found, the application and the upper layer are notified. The relative independence of the working process of the protocol module and the complete autonomy of the physical layer protocol for the search process can minimize the interaction between the protocol layers when searching for cells without a network, thereby reducing the power consumption of the mobile terminal. Therefore, the physical layer search The method is the key to the power consumption and service quality index of the whole mobile terminal.

In the selection of the physical layer search method, the search period and search capability are decisive, and the search capability is related to the physical layer algorithm. The present invention mainly studies how to select a suitable search period. The search cycle here refers to the time interval between two frequency band search actions before and after. The larger the search period, the longer the sleep time, which is more conducive to the power saving of the mobile terminal, but the slower the response to the signal recovery in the no-network environment, the smaller the search period, the increased power consumption of the mobile terminal search, but it can It is easier to quickly detect the recovery of network signals and search for available cells.

For this reason, the present invention proposes a method for searching a mobile terminal without a network cell, including: obtaining a wireless network search frequency band; performing a frequency band search, when the frequency band search is successful, enter the cell search, otherwise, adjust the frequency band search cycle, and enter no network sleep state; carry out cell search, when the cell search is successful, end the no-network cell search process, otherwise, adjust the frequency band search cycle and enter the no-network sleep state; when the duration of the no-network sleep state reaches the adjusted frequency band search cycle, Go back and perform the band search.

This method associates the success and failure information of the intermediate process of frequency band search and cell search as the signal change trend in the no-network environment, and dynamically adjusts the cell search cycle of the mobile terminal without network accordingly, reducing the power consumption of the terminal in the no-network search state. At the same time, the cell can be quickly searched when the network signal is restored.

The above is the core idea of the present application. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention. rather than all examples. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Embodiment one:

Referring to FIG. 1 , it is a schematic flow diagram of a method for searching a mobile terminal without a network cell provided by an embodiment of the present invention. The method includes the following steps:

Step S201, acquiring a frequency band without network search.

After the mobile terminal fails all attempts to search for the cell, it enters the no-network search process. The high-level protocol arranges the search frequency band and notifies the physical layer according to the RAT (Radio Access Technology) supported by the terminal. The RAT includes GSM, GPRS, EDGE, TD-SCDMA, TD-LTE, WCDMA, CDMA2000 and so on.

Step S202, perform a frequency band search, and determine whether the frequency band search is successful. If the frequency band search is successful, go to step S203; otherwise, go to step S204.

Step S203, perform cell search, judge whether the cell search is successful, if the cell search is successful, end the no-network cell search process, otherwise, go to step S204.

After the cell search is successful, it is considered that there are cells available to the mobile terminal in the current network environment. At this time, the no-network cell search process ends, and the physical layer protocol reports the searched cells to the application layer and other high-level layers.

Step S204, adjusting the frequency band search cycle.

Step S205, entering into a sleep state without network. When the duration of the no-network sleep state reaches the adjusted frequency band search period, return to step S202.

Embodiment two:

In the method for searching a cell without a network for a mobile terminal provided in Embodiment 1, the frequency band search may specifically include the following steps:

Step S301, according to the no-network search frequency band and RAT information, search frequency bands under different RATs.

Step S302, calculating received signal strength indications of frequency points under each RAT, and obtaining a frequency point power search list.

Calculate the RSSI (Received Signal Strength Indication, Received Signal Strength Indication) of frequency points that may exist under each RAT, and obtain the power search list, as shown in formula 1:

RSSI _rat(i) , j={RSSI _j }, j=0, 1, 2...N _max (Formula 1)

Wherein, rat(i) is a different access mode, and N _max is the maximum number of frequency points in the corresponding access mode.

RSSI is the power strength calculated by the terminal according to the wireless received signal, including the signal and interference part, which can be used to preliminarily judge the presence or absence of wireless signals in the current network environment and the distribution of strength and weakness.

Step S303, judging whether there are frequency points exceeding the preset power threshold, if yes, the frequency band search is successful, otherwise, the frequency band search fails.

According to the preset power threshold P _{th, rat(i)} , filter the frequency points exceeding the RSSI power threshold, if the power measurement values of the frequency points supported in all access modes do not exceed the corresponding power preset threshold, it means that the frequency band search Fail, quickly end the current search process, no network sleep state; if there are frequency points exceeding the preset power threshold, otherwise, the frequency band search is successful.

If the frequency band search fails, it means that the current network has no coverage at all, and the search cycle of the mobile terminal without a network cell should be greatly increased, that is, the time interval between two frequency band search behaviors before and after is increased, and the increased duration is the first duration. The specific implementation method can be as follows:

Adjust the frequency band search period according to formula 2 and formula 3,

$\left\{\begin{array}{c}{T}_{\mathrm{cs}}={\mathrm{\β}}^k\×T_f\\ k\∈[K_{\min },K_{\max }]\end{array}\right.$ (Formula 2),

When the frequency band search fails, set the value of k according to formula 3,

k=k+step 1 (Formula 3),

Among them, T _cs is the frequency band search cycle, its unit can be second, T _f is the preset fixed value, β is the preset cycle adjustment factor, k is the adjustment parameter, K _min is the initial value of k, K _max is k The maximum value of , step1 is the preset adjustment step size. K _min can be used to limit the minimum value of k to prevent frequent search operations from increasing the power consumption of the terminal, and K _max can be used to limit the maximum value of k to prevent the terminal from being unable to know the recovery of the network signal in time due to the long search period.

In addition, the selection of the preset power threshold P _{th, rat(i)} is not only the basis for judging the success or failure of the frequency band search, but the number of frequency points obtained after filtering also affects the time of the subsequent search process, so the preset power threshold The rationality of P _{th, rat(i)} is particularly important. Therefore, the method for searching a cell without a network for a mobile terminal provided in the embodiment of the present invention may also include after the frequency band search is successful:

updating the preset power threshold. The method of updating the power threshold is as follows:

Calculate the power smoothing value of the frequency points that currently exceed the preset threshold power;

A smoothing operation is performed on the original preset power threshold and the power smoothing value of the frequency point whose power exceeds the preset threshold to obtain a new power threshold, and the newly obtained power threshold is set as the preset power threshold.

Its specific implementation method is as follows:

Calculate the power smoothing value P _{smth, rat(i)} of the frequency points that currently exceed the preset threshold power according to formula 4,

$P_{\mathrm{smth},\mathrm{rat}\left(i\right)}=\underset{\mathrm{no}=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\α}}_{\mathrm{no}}\×{\mathrm{RSSI}}_{\mathrm{no}}$ (Formula 4),

Among them, N is the number of frequency points whose power exceeds the preset threshold, α _n is the weight coefficient of the frequency point, and RSSI _n is the power value of the frequency point;

In order to increase the reliability of the preset power threshold and reduce the impact of the instantaneous signal mutation, the two preset power thresholds are smoothed according to formula 5:

P _{th, rat(i)} = λ × P _{th, rat(i)} + (1-λ) × P _{smth, rat(i)} (Formula 5),

Wherein, P _{th, rat(i)} is a preset power threshold, P _{smth, rat(i)} is a power smoothing value of a frequency point whose power exceeds the preset threshold power, and λ is a smoothing coefficient. The initial value of the preset power threshold P _th,rat(i) may be the minimum demodulation sensitivity level in each access mode.

In order to make the subsequent cell search more high-quality and efficient, improve the search quality, and further reduce the power consumption of the search, after the frequency band search is successful, it may also include:

Arranging the list of frequency points exceeding the preset power threshold in order of power from strong to weak;

The cell search is performed according to the order of frequency point power list from strong to weak.

In this embodiment, other steps and Embodiment 1 can be referred to each other, and will not be repeated here. In the technical solution provided by this embodiment, the RSSI measurement result reflects the signal power distribution of the search frequency band, and according to the preset power threshold value, if the RSSI measurement result is lower than the power threshold, it will be judged that there is no network signal, and the search period will be adjusted according to the frequency band search result. The set power threshold makes the subsequent cell search more high-quality and efficient, improves the search quality, and further reduces the power consumption of the terminal in the state of no network search.

Embodiment three:

For different access cell systems, the frame structure, modulation and coding methods are different, and the implementation details of different terminal manufacturers are also different, but the basic method and process of cell search are generally similar, so the cell search process is roughly divided into coarse There are three sub-processes of synchronization, fine synchronization and reading system information. Therefore, referring to FIG. 4 , in the mobile terminal network-free cell search method provided in Embodiment 1, the cell search may specifically include the following steps:

Step S401, coarse synchronization, refers to acquiring initial synchronization of frame timing, if successful, proceed to step S402, otherwise, cell search fails. The detection success of the synchronization channel (or reference signal, synchronization sequence) is the only reliable information for judging the success or failure of the process. In this step, the cell search may be performed in sequence according to the frequency band power from strong to weak.

Step S402, fine synchronization, refers to obtaining precise synchronization of frame timing and cell ID, if successful, proceed to step S403, otherwise, cell search fails. Whether the cell ID is obtained successfully is the only reliable information to judge the success or failure of the process.

Step S403, reading system information refers to performing downlink reception, demodulation, and decoding on the broadcast channel, and reading the network frame number. If successful, the cell search is successful; otherwise, the cell search fails. The result of CRC (Cyclic Redundancy Check, decoding cyclic redundancy check) is the only reliable information to judge the success or failure of the process.

Taking the TD-LTE system as an example, coarse synchronization refers to the PSS signal detection process, and fine synchronization refers to the SSS signal detection process. If the SSS signal detection is successful, the cell ID is calculated according to Nid1 and Nid2. In the TD-SCDMA system, coarse synchronization refers to the process of obtaining DwPTS detection, and fine synchronization refers to the detection process of the basic Midamble code. If the detection of the basic Midamble code is successful, the corresponding cell ID will be output. In the GSM/GPRS/EDGE system, coarse synchronization refers to the detection FCCH channel, fine synchronization is to detect SCH channel.

Among the above three sub-processes of cell search, the success of the previous process is always a necessary condition for the start of the next process. Once a certain process fails, the entire cell search process fails. During the process of cell search, the success or failure information of each process under different RATs is recorded. As long as an available cell is found in any access mode, the cell search is successful.

According to the failure indications at different stages in the cell search process, different adjustment steps can be selected to update the cycle of the next mobile terminal without network cell search, and the frequency band search cycle can be adjusted as follows:

When the coarse synchronization fails, increase the time interval between the two frequency band search behaviors before and after, and the increased duration is the second duration;

When the fine synchronization fails, reduce the time interval between the two frequency band search behaviors before and after, and the reduced duration is the third duration;

When reading the system message fails, reduce the time interval between the two frequency band search actions before and after, and the reduced time length is the fourth time length.

Its specific implementation is as follows:

Calculate the cycle of mobile terminal no network cell search according to formula 6:

$\left\{\begin{array}{c}{T}_{\mathrm{cs}}={\mathrm{\β}}^k\×T_f,\\ k\∈[K_{\min },K_{\max }]\end{array}\right.$ (Formula 6),

When the coarse synchronization fails, update the value of k according to formula 7:

k=k+strp 2 (formula 7);

When fine synchronization fails, update the value of k according to formula 8:

k=k-step 3 (formula 8);

When reading system messages fails, update the value of k according to formula 9:

k=k-step 4 (formula 9);

When the system information is successfully read, that is, after the cell search is successful, the frequency band search period can be set to the initial value, which is implemented in the following manner:

Update the value of k according to Equation 10: k=K _min (Equation 10).

Among them, T _cs is the frequency band search cycle, its unit can be second, T _f is the preset fixed value, β is the preset cycle adjustment factor, k is the adjustment parameter, K _min is the initial value of k, K _max is k The maximum value of , in order to avoid infinite increase of sleep time, limit the maximum k to not exceed K _max , and step2, step3 and step4 are preset adjustment step sizes. K _min can be used to limit the minimum value of k to prevent frequent search operations from increasing the power consumption of the terminal, and K _max can be used to limit the maximum value of k to prevent the terminal from being unable to know the recovery of the network signal in time due to the long search period.

In addition, if the frequency band search fails, it can be considered that the network has no coverage at all, and the search cycle needs to be greatly increased. If the rough synchronization fails, it is considered that the quality of the network signal is poor, and it cannot provide corresponding services for mobile terminals, and the search cycle needs to be increased. , therefore, the first duration may be constrained to be greater than the second duration. Specifically, the step1 is constrained to be greater than the step2.

If fine synchronization succeeds in obtaining the cell ID, it is considered that the network signal is recovering, and the search period needs to be shortened. If the system information is read successfully, it is considered that there is an available cell in the network environment, and the search period needs to be greatly shortened. Therefore, all The fourth duration is greater than the third duration. Specifically, the step1 is constrained to be greater than the step2.

In this embodiment, other steps and Embodiment 1 and Embodiment 2 can be referred to each other, and will not be repeated here. In the technical solution provided by this embodiment, the cell search process is divided into obtaining coarse synchronization of cells, fine synchronization of cells, and reading In the process of obtaining cell system information, the corresponding search cycle adjustment step is selected according to the success and failure indication information of these steps. The success and failure indications of cell search at different stages represent the signal quality of network coverage, interference level and other information. These information can be used to quickly track the change trend of the network signal, and correspondingly dynamically adjust the cell search cycle of the mobile terminal without network, while reducing the search power consumption, the cell can be quickly searched.

By applying the technical solution provided by the embodiment of the present invention, by associating the success and failure information of the intermediate process of frequency band search and cell search with the signal change trend in the no-network environment, the network signal change trend can be quickly tracked by using these information, and the corresponding Dynamically adjust the cell search cycle of the mobile terminal without network, while reducing the power consumption of the terminal in the state of no network search, it can quickly search for the cell when the network signal is restored.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other. The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (7)

1. a non-network cell searching method of mobile terminal, is characterized in that, comprising:

Obtain the wireless network search frequency range;

Carry out frequency band search, when the frequency band search success, enter Cell searching, otherwise, adjust the frequency band search cycle, and enter without the network sleep state, in the wherein said adjustment frequency band search cycle, comprising:

In the time interval of twice frequency band search behavior before and after increasing, the duration of increase is the first duration;

Carry out Cell searching, when the Cell searching success, finish without the network cell search procedure, otherwise, to adjust the frequency band search cycle, and enter without the network sleep state, wherein said Cell searching comprises:

Carry out slightly synchronously, if success enters carefully synchronously, otherwise in the time interval of increase by the twice frequency band search behavior in front and back, the duration of increase is the second duration;

Carry out carefully synchronously, if success enters read system message, otherwise in the time interval of twice frequency band search behavior before and after reducing, the duration that reduces is the 3rd duration;

Read system message, if success, Cell searching success, otherwise in the time interval of twice frequency band search behavior before and after reducing, the duration that reduces is the 4th duration;

Frequency band search week after date after dormant lasting duration reaches adjustment without network, return to and carry out described frequency band search.

2. method according to claim 1, is characterized in that, after the Cell searching success, also comprises:

The available cell that searches is reported application layer, and the frequency band search cycle is set to initial value.

3. method according to claim 1 is characterized in that:

Described the first duration is greater than described the second duration.

4. method according to claim 1 is characterized in that:

Described the 4th duration is greater than described the 3rd duration.

5. method according to claim 1, is characterized in that, described frequency band search comprises:

According to without web search frequency range and access module information, the frequency range under different access modules is searched for;

Calculate the received signal strength indicator of frequency under each access module, obtain the frequency power list;

Judge whether to exist the frequency that surpasses default power threshold, if so, frequency band search success, otherwise frequency band search failure.

6. method according to claim 5 is characterized in that:

After frequency band search success, according to power by strong to the weak arranged sequentially described frequency that surpasses default power threshold;

Carry out described Cell searching according to frequency power list intermediate-frequeney point power by strong extremely weak order.

7. method according to claim 5, is characterized in that, after the frequency band search success, also comprises, upgrades as follows described default power threshold:

Calculate the current power smooth value that surpasses the frequency of default power threshold;

Former default power threshold and the current power smooth value that surpasses the frequency of default power threshold are carried out level and smooth computing, obtain new power threshold, the power threshold that the power threshold that newly obtains is set to preset.

Images